This application claims priority of Taiwanese application no. 091206676, filed on May 10, 2002.
1. Field of the Invention
The invention relates to a saw blade chuck, more particularly to a quick release saw blade chuck which can retain releasably one end portion of a saw blade to a driving arm of a scroll saw.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional scroll saw is shown to include a pair of upper and lower driving arms 12, 13 that hold a saw blade 11 therebetween, a lower blade holder 14, an upper blade holder 15, a blade tension adjusting device 16 and a compression spring 17. The saw blade 11 has a headed upper end portion 111 and a headed lower end portion 112 opposite to the upper end portion 111. The lower blade holder 14 has a mounting end 141 mounted fixedly on the lower driving arm 13, and a blade holder portion 143 that is formed with a notch 142 for engaging the lower end portion 112 of the saw blade 11. The upper blade holder 15 has a mounting portion 151 mounted pivotally to the upper driving arm 12, and a blade holder portion 153 that is formed with a notch 152 for engaging the upper end portion 111 of the saw blade 11. The blade tension adjusting device 16 includes a threaded shank 161 that extends threadedly through the upper driving arm 12 and that is connected to the upper blade holder 15 at one end, and a rotary knob 162 mounted on the other end of the shank 161. The compression spring 17 is sleeved on the shank 161, and has one end abutting against the upper driving arm 12 and an opposite end abutting against the mounting portion 151 of the upper blade holder 15.
In use, with the end portions 111, 112 of the saw blade 11 engaging the upper and lower blade holders 14, 14, rotation of the rotary knob 162 in a first direction causes the shank 161 to move upwardly relative to the upper driving arm 12, thereby causing the upper blade holder 15 to pivot in a first direction for increasing tension of the saw blade 11 and preventing removal of the saw blade 11 from the upper and lower blade holders 15, 14, as shown in FIG. 1. On the other hand, rotation of the rotary knob 162 in a second direction opposite to the first direction causes the shank 161 to move downwardly relative to the upper driving arm 12, thereby causing the upper blade holder 15 to pivot in a second direction opposite to the first direction for permitting removal of the saw blade 11 from the upper and lower blade holders 15, 14 for replacement purposes, as shown in FIG. 2.
The following are some of the drawbacks of the conventional scroll saw:
1. Quick attachment or removal of the saw blade 11 is not possible because of the need to rotate the rotary knob 162 before the upper blade holder portion 153 can be moved to engage or disengage from the upper end portion 111 of the saw blade 11.
2. Proper adjustment of the saw blade tension cannot be conveniently conducted due to the threaded engagement between the shank 161 and the upper driving arm 12. When the tension of the saw blade 11 is too high, the saw blade 11 tends to break easily. On the other hand, when the tension of the saw blade 11 is too low, the saw blade 11 tends to wobble during a cutting operation.
Therefore, the main object of the present invention is to provide a quick release saw blade chuck that can overcome the aforesaid drawbacks associated with the prior art.
Accordingly, a saw blade chuck of this invention is used to retain releasably one end portion of a saw blade to a driving arm of a scroll saw, and comprises:
a blade retaining unit having a mounting portion adapted to be mounted pivotally on the driving arm, and a blade holder portion that extends from the mounting portion, the blade retaining unit being pivotable relative to the driving arm to pivot from a first position, where the blade holder portion is adapted to engage the end portion of the saw blade, to a second position, where the blade holder portion is adapted to disengage from the end portion of the saw blade;
a biasing unit for biasing the blade retaining unit to pivot to the first position; and
a pushing unit operable so as to provide a pushing force for pushing the blade retaining unit in a linear direction to cause the blade retaining unit to pivot to the second position against biasing action of the biasing unit.